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Re: Motor stalled.......
Losmandy no longer repair G1 L
Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 09 October 2017 05:27 To: Losmandy_users@... Subject: [Losmandy_users] Re: Motor stalled....... John Seen this before in DEC and RA, repaired a DEC one not long ago (hope its not same one doubt it).. Unfortunately it's a bad DEC encoder IC. Yes there is a remote possibility its a DEC motor itself or DEC H bridge but I'm pretty sure its as I said. Upon switch on both motor pinions lock...aka they are applied drive voltages on both sides of their H bridges. Their pinions will have major resistance to movement and be difficult to turn (if you can and do it will log a boot fault in the HC). When you see the HC msg "system boot at xxxx....xx" the Ra pinion starts driving at sidereal rate., the DEC will stay locked resistant to movement and will only move if commanded. On the system I repaired that had the same symptoms and bad DEC encoder IC (above), the DEC pinion was weak and rotated slowly on pwr on and drove crazy if one of the HC DEC buttons was pressed. Both Ra/DEC motor encoder ICs U15/16 are firmware installed. Repairer: Rene? (Germany); David Partridge (UK); Michael Herman (USA); Me (Australia); Losmandy (USA)...anyone I miss? Brendan [Non-text portions of this message have been removed] |
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Re: Motor stalled.......
Most likely problem here is either the motor shaft encoder, followed by the quadrature decoder ICs.
I can fix either of these problems (I live in the UK) as I am sure can Michael Hermann (CA) and Bren Smith (Australia). Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 09 October 2017 02:03 To: Losmandy_users@... Subject: [Losmandy_users] Motor stalled....... Hello all, New member here, with a problem. Ok, I just picked up a used G11 with Gemini 1 level 4 version 1.05. When trying to align to a bright star the dec motor show's motor stall. I figured something must be binding, so I took out the motor and tried it again, same thing, eliminating possible worm binding. After restarting the system I noticed that after putting the mount in sidereal rate the ra motor seems to spin at a that I would expect but the dec gear is spinning at a few hundred rpm not with enough torque to move the mount. Then when I try to align on the hand controller, it speeds up to a high rpm for a split second then shows the error. When turned off the motor turns by hand freely. The power supply that came with it is at 12v so I tried a higher voltage one at 14.5v, no different. Where do I start? Thanks John |
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Re: Motor stalled.......
If it is the U15 or U16 chip, then David Partridge in the UK has these or can make them. I have not yet tackled that.? These chips are in sockets on the main board and can easily be? pulled out (say with an automotive sharp hook tool) and replaced by the owner. If it is the motor's encoder element, then, again, I have no experience with that trouble.?? In either case, I am surprised the prior owner did not experience the problem and that John, who? just acquired the system, is stuck with this problem from his first experience.?? Best of luck, Michael On Sun, Oct 8, 2017 at 9:26 PM, brenatlilydale@... [Losmandy_users] <Losmandy_users@...> wrote:
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Re: Motor stalled.......
hmmmm... a good puzzle.... Try this: set the Gemini to "terrestrial" tracking which means it will not drive RA or DEC.? ? If you do that, neither RA or DEC should move. If the Gemini is still driving the DEC, there is one possible cause: the handset serial cable, or the handset itself can have an intermittent contact in the diamond switch (North South butttons moves the DEC only).? ?Try removing the handset from its cable.? If the DEC stops moving, then it is a flaw or short in the handset.?? To remedy that, unscrew the 2 Phillips screws in back of the handset. Open the handset case.? Look for and clean any discoloration or residue on the ribbon cable or its connector, and on the circuit board, using a cotton swab dipped in alcohol.? Usually this clears up any slight surface short.?? Hope you get this cleaned up and enjoy your system... Best, Michael? On Oct 8, 2017 18:58, "mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users]" <Losmandy_users@...> wrote:
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Re: Motor stalled.......
Hi, I would do a few things: First, contact the seller and talk about what you are experiencing.? Is that why they sold the mount?? ?If you cannot fix this can you return it? Second, to try and fix the problem, see if there is oxidation or corrosion on the cable connector pins.? If there is poor contact, then the signals from the motor encoders will be missing or noisy, and the (Gemini) will try to run the motor looking for the encoder signal.? If the encoder is bad, the system will just keep trying to put in power to get a signal.?? Third, ... sometimes cables go bad also.? Try swapping the RA and DEC cables. ? ?Be very very careful putting on the cables.? There is a "dent" identifier on the cable connector, but these cables can be forced into their sockets with damaging consequences.? In the dark it is easy to make a damaging error.?? Fourth, be sure the Gemini says it is connected to a G11 mount.? There are many mount options and sometimes the system (especially with a weak/bad internal 3V backup battery) will default to a different model mount.?? I'm out of ideas for you.... sorry! Best, Michael On Sun, Oct 8, 2017 at 6:03 PM, mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users] <Losmandy_users@...> wrote:
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Tightened clutch = drag in RA axis of GM-8
I recently decided to tear down my GM8 for cleaning and re-lubing for the first time and, what I thought was a lubrication issue has turned into what could possibly be another case of shaft misalignment, although I have yet to completely wrap my head around what I am seeing... On the RA axis, I am getting drag as the clutch is tightened and have found clear witness marks on the RA shaft that confirm what is happening. On the RA shaft, directly adjacent to the outer (lower) bearing race are the noted marks (I have loaded three photos in album labeled photon_trap) where the ID of the bearing or maybe the outer race is coming in contact with the shaft resulting in considerable drag. I could remove a few thousandths of an inch from the shaft but not fully understanding why this is happening (other than a better design might have provided a shoulder for the bearing ID to ride on like at the other end) I am very hesitant to do that. I see no gap around any of the bearing block to center section interfaces (will not accept .0015 feeler gauge) Also, I have been using the "improved" wave washer position between the knob and aluminum spacer and have removed the wave washer completely with the same result. It seems the rotation of the clutch knob is somehow forcing the bearing to one side until it contacts the shaft. I have also noticed minor witness marks on the shoulder on the worm end of the shaft from the bearing/race ID, no where as severe as those pictured - more like wear marks, probably normal. In searching, I have found others to have similar symptoms but I am not sure my situation is the same -- Any insight is appreciated Jeff |
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Re: G11 Polar Alignment hole
Yes...we all have this design of the polar bore hole.?? I always wondered why...? I think it is the same kind of offset with the Meade LXD55 mount, but the Orion/Synta Atlas bores it exactly perpendicular....I was expecting it to be perpendicular.? ? ? At least it is not an egg-shaped hole!?? Best, Michael? On Oct 7, 2017 08:47, "Nels Johnson nhbj6@... [Losmandy_users]" <Losmandy_users@...> wrote:
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David C. Partridge
Michael Herman
photon_trap